I am thinking about the Employment Tribunal as the employer is refusing to put adjustments in place. I am in an open plan office which is horrible experience for me every day. I am unhappy there. I cannot focus. I can only think all the time about how to escape from this.

You might wanna consider applying for a new job as well, since the employer have already refused you a solution. All you can get now (or not, as we concluded here) is money compensation. You still need another job if you are going to be happy.